Question: If $f(x) = 2x + 3$, what is $f(4)$?
1. **State the problem:** We are given a function $f(x) = 2x + 3$ and asked to find the value of $f(4)$.
2. **Recall the formula:** The function $f(x)$ means for any input $x$, the output is calculated by $2x + 3$.
3. **Substitute the value:** To find $f(4)$, replace $x$ with $4$ in the formula:
$$f(4) = 2 \times 4 + 3$$
4. **Calculate step-by-step:**
$$f(4) = 8 + 3$$
$$f(4) = 11$$
5. **Conclusion:** The value of $f(4)$ is $11$.